Knowledge, not Numbers
by authenticaussie
Summary: "You should date April," Donnie blurts in an angry rush. Casey's grin freezes, tight and uncertain. / Or: Donnie codes a program to tell him who he's allowed to date. It backfires.


**AN: ****title from "A good decision is based on knowledge and not on numbers." - Plato**

**Also: hi! I'm new here and taking tmnt reqs on tumblr because _they're kids and I love them_**

**from anonymous: Donnie decides he's going to prove scientifically that his crushes are stupid so he codes the World's Best Dating Software, and it says Casey and April should date so he doesn't check his own name**

* * *

"So, I ran the numbers-"

"How fast were they?"

Donnie glares at him, but April's smothering laughter behind her hand so Casey counts that as a win.

"I _crunched _the-"

"Did they taste good?"

"_You should date_," Donnie blurts in an angry rush. Casey's grin freezes, tight and uncertain.

"What?" he says.

"How do numbers-?" April mutters, then holds her hand up. "Date _who_? It's not like saving the world gave us much time to meet new people." She smiles at Donnie, teasing and light, but there's an edge to her smile that Casey can only catch because of the time they've spent together. He looks to Donnie, watching as Donnie sinks a little, defensively, into his shell.

"Not new people," Donnie mumbles, and then he takes a deep breath and pulls himself out of his shell. Shoulders back, head high, the pose of a dutiful son trained into him, but he's looking at the wall over their shoulders instead of at them and Casey feels a frown start to pull at his mouth. "You should date each other." Donnie looks to Casey, a familiar, frustrated scowl on his face as he picks his next words carefully, "I made a program, for- to see if I- no. To see if you two would be- to prove that you'd be bad for each other. And it- proved I was- wrong."

Casey turns the start of his frown into a teasing smile, trying to crush the uncomfortable feeling growing in the pit of his stomach. "Think that could've sounded anymore painful, D? And, hey, mind repeating it so I can get a recording?"

"Casey…" April says, in the soft tone that means he's overstepped some boundary, and he knows it but he can't- Donnie _can't _be serious.

"No way, Red. This is a once-in-a-lifetime opportunity. When does Donnie ever say he's wrong?"

"_Casey_," she says, and leans into his space to pinch the back of his hand. He grabs her wrist, pulling it behind her back, and she twists out and over the back of the couch and he lets her go-

She covers his mouth, and he thinks about licking her palm, but decides to give her and her empathy powers the floor. _For now_, he thinks, frowning as Donnie shifts on his feet.

"I made a program that analysed- the viability of relationships," he says softly when April stays silent, looking at him. "It proved that you and Casey's efficiency in battle would improve by approximately 20%, as would his grades and your general happiness, April. That's- you two being happy is _important_."

"So why do you look so unhappy right now, Don?" she asks, and takes her hands away from Casey's mouth. Slowly, so he knows not to speak, but something about Donnie's posture, the expression on his face, tells him it's wiser to shut up.

Donnie manages a smile for her, because he always will, but even Casey can tell something is off about it. To April's powers it must look like a neon siren. "You heard Casey, April. This is pretty rare for me - I don't like being proved wrong."

"What were you trying to prove _right_?" she asks, and Donnie stiffens.

"April-" he says, and then, "don't-"

Donnie scrubs at his face roughly and just before he pulls his mask back down, Casey catches the dark bags under his eyes. This hadn't been some idle project; he'd poured sleepless hours into it, and for what? To be told by a machine - Donnie's religion, if ever he'd believe in a god - that April and Casey should date. Why had he even been _doing _that?

"Donnie," she says, in the tone she uses when she wants something, when she wants _answers, _and Donnie crosses his arms over his plastron. "Why were you making a program to prove Casey and I should-" she pauses, her voice dipping pained, and Casey tries to ignore the sting, "-date?"

"It was to prove you shouldn't date," Donnie mutters. "And it backfired."

"Not an answer to 'why'," Casey says shortly, and Donnie glares at him.

"So I used the program to help me analyse common romantic scenarios," Donnie says, ignoring Casey entirely as he pulls a sheet of paper out of his belt and unfolds it in front of them. It's colour-coded, because of course it is. "And I figured out the most efficient dating plan. Being in life-threatening danger together has actually helped the plan a lot; there's a whole section here you can skip if you want to."

"_Donnie," _April says, and the second her hands are off Casey's shoulders, he's up and pulling the plan out of Donnie's hands. Donnie makes a pained little noise as it flutters to the floor.

"_Look," _he says, poking Donnie in the chest hard enough that Donnie startles backward. "I know you're still bad at people interacting and all that bs, but you don't just do this stuff, D, got it? I'm not gonna date April just because some stupid program says I should, not when she's been _more _than clear on not wanting a boyfriend right now, and I sure as hell ain't doing it based on a _chart. _We're not gonna date just because some stupid program says so."

"It's not stupid," Donnie says, and he reaches for his chart but Casey shoves him again, ignoring April's _hey! _in the background.

"It is too. You're stupid if you think some machine gets to tell me who to date and how to do it. It's stupid."

"It is _not!" _Donnie says, baring his teeth, and he finally looks normal. He's finally snapping back like he should, all loose-limbed and slouched shoulders drawn tight in indignation. "I don't make _stupid _things, it isn't stupid, I spent hours on it! I programmed it with Professor Honeycut's simulator tech, it can run thousands of scenarios and extrapolate the likelihood of common threads working in real life-"

"_Stupid," _Casey says, and Donnie snarls.

"_You're _stupid!"

"I'm not the one who made a useless machine!"

"It is not!" Donnie says, and he shoves Casey, making Casey stumble back over his own feet before he lunges forwards and into Donnie's space again.

"Oh yeah? Then what's it do but tell you bull about me and April dating?"

"It proved my crush on you two is _stupid_!"

"Will you both _stop it_?" April yells, shoving both of them apart with her hands and her powers, and Casey's too stunned to catch himself, falling back onto the couch. Donnie hits a beanbag and goes down too, his eyes wide.

April, between them both, is panting hard as her arms drop to her sides. Her hair is loose around her shoulders, and usually Casey would go to her side to keep her up while Donnie pressed his hand to her forehead, then to check her pulse, but right now Donnie looks like he's about to bolt and Casey's still reeling.

Silence reigns in the lair, some water drip echo the only distant noise, and then Donnie says, "I didn't mean that."

His voice is too soft, too scared, to be anything but a lie.

Casey doesn't know if they're supposed to let Donnie get away with it.

* * *

**AN: ****...I'm a big baby who couldn't figure out how to end it but do pls imagine April "I literally have psychic powers" O'neil going: "donnie are you kidding you feel like you're gonna cry we are fixing this right now you're my best friend. also I didn't want A boyfriend I wanted *two* and I couldn't decide. this solves my problem entirely." (or, hey, hmu on tumblr with Ideas on how you think it'd go and I'll see if I can write more :D)**

**also I honestly think casey would be SUCH an awkward bean about Actually Having Deep Feelings (and any discussion thereof) so even tho he's a blunt dumbass, having a Sudden ConfessionTM sprung on him makes him clam up and panic.**

**ANYWAY I love hearing reviews, pls tell me what you thought, and feel free to hmu on tumblr authenticaussie if you want any reqs~! I've seen most of 2012, all of Rise, and parts of 2003 (I'm Working On It lmao.)**


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